Do I need to create a proxy server?

Since I was just testing the original setup of ISPConfig last year I installed it on a Celeron Compaq machine that should probably die in a year or two. I have about 5 websites on the server right now, but as you probably already known some web application have some latency on that Apache server. Especially those with images and large files.

Should I create a proxy server that has a faster processor, more RAM, and just a better machine? If so how should I go about doing so? Can ISPConfig support proxy servers? Should I also think about load-balancing? We are a company with limited funds so we don't plan on purchasing a new server for another year. What do you suggest I do?